Heat Pumps should be located such that the air exhausted from one heat pump is not pulled in by the other (see below). 

Provide a subpanel within reach of the twin-SANCO2 units in accordance to NEC and local codes

This setup enables the twin heat pumps to function as if there was only one heat pump, but with twice the capacity of a normal SANCO2 unit. 

The Harvest Thermal Pod directly controls one heat pump -- the primary heat pump -- while the second heat pump is controlled by a current sensing switch. This current sensing switch is located only on the power line of primary heat pump, and switches on (turning on SANCO2 - 2) after a minimum amount of current flows to primary heat pump

The thermistor connection to primary heat pump will be typical of a Harvest Thermal single heat pump system, and the secondary heat pump will have a simple resistor installed on its thermistor connection that matches the resistance of the thermistor measuring a “‘cold” tank temperature. 

Single SANCO2 Heat Pump Setup

Twin-SANCO2 Additional Setup Information

Tank

Installation Manual - Classic

System Overview

Compatibility

Safety

Before You Begin

Heat Pump Water Heater - SANCO2

Harvest Pod

Airscape Air Handler Unit

(Deprecated) Optional ECOer Heat Pump AC

Integrating DHW Recirculation

Components

Single SANCO2 Plumbing Diagram

Twin SANCO2 Plumbing Diagram

Double-Tank Plumbing Diagram

Plumbing System Diagrams

Insulation

Cold Climate Installations

SANCO2 Low Voltage Wiring

Low Voltage Wiring Diagram

Airflow Sensing

Twin SANCO2 Additional Sensor Wiring

Wiring

Hydronic System Start Up

ECOer Heat Pump A/C Start Up

Thermal Battery System Start Up

Start Up

Troubleshooting

Installation Manual